This invention relates to backhoes, and more particularly, to an improved severe duty grapple with a tubular pivot.
Bulldozers, front-end loaders and trucks have long been used for road work, clearing brush, and demolition of condemned buildings. In the early 1970's, grapple assemblies on a backhoe boom were developed and have proved to be extremely valuable for a variety of uses, especially for building demolition. Grapple assemblies typically have a pivotal upper jaw and a fixed lower jaw. Grapples can be used for crushing, raking and loading of debris. Examples of such early grapples are disclosed in U.S. Pat. Nos. 3,802,731; 4,017,114; 4,248,471; and 4,413,945.
Over the years since the early 1970's, grapples have still pretty much remained the same and are illustrated in FIGS. 1-3. Backhoe grapple assembly 10 is typically pivotally connected to the stick and further connected with the stick through actuators or cylinders 14 and optionally rigid linkages 16. Stick 12 is connected to the boom which is connected to the backhoe which would utilize a grapple.
Past grapple assemblies would typically include an arcuate-shaped upper jaw or clam shell 18 with rake tips 20 having a backside 26 with stick mount plates 28. Opposite the rake tips 20 is the inner end 22. Load engaging plates 24 are typically between the rake tips 20 and the inner end 22. A lower arcuate-shaped jaw or clam shell 32 similarly has rake tips 34 opposite from the inner end 36 in between which are located load engaging plates 38. On the backside 40 of the lower jaw 32 are stick mount plates 42. The stick mount plates 28 and 42 are suitably connected to the stick 12 of the backhoe and further connected by linkages with the cylinder 14 and linkage 16 or alternatively another cylinder 14 should the lower jaw 32 be desirably moveable.
As can clearly be seen, prior backhoe grapple assemblies 10 have a substantially open throat 50. The upper jaw 18 suitably has two upper lug plates 56 with eyelets into which are welded two machined sleeves 58 into which are mounted 2 pivot bushings 60. On the lower jaw 32 are located 4 lower lug plates 62 with eyelets each having a welded machine sleeve 64 welded into each eyelet. Two pivot pins 66 are utilized in the prior grapple assemblies of FIGS. 2 and 3 while a single pivot pin 68 may be utilized in the grapple assembly of FIG. 1. The pivot pins 68 or 66 are suitably held in place such as by a keeper 70.
The most significant problems with prior known grapple assemblies 10 is that the substantially open throat 50 allows debris D to get into the throat 50 to possibly abrade and cut into lug plates 56 and 62 as well as wear on pivot pin 66 or 68 and sometimes possibly nicking and damaging the rams of the actuators or cylinders 14 all of which can eventually render the grapple assembly 10 to be inoperative requiring replacement, rebuilding or significant repair.
Another significant problem is that the lug plates 56 and 62 of the upper and lower jaws 18 and 32 wear upon each other eventually causing significant slack and sloppiness in the operation of the jaws 18 and 32 with respect to each other. This also means that the grapple becomes extremely noisy with more wear during its operation.
Another significant disadvantage of past known grapple assemblies includes the multitude of parts to include 6 lug plates 56 and 62, and six machined sleeves 58 and 64 to be welded in place along with the associated wear of all of these parts.
There is a need for a severe duty grapple that will not utilize so many lug plates and machined sleeves that will have a substantially closed throat that will provide for extended operation without rebuilding in a smooth fashion with all of the stick mounts, lug plates, pivot pins being protected from damage caused by debris otherwise in an open throat 50.